@sebastbake/music-tempo

<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <base data-ice="baseUrl" href="../../"> <title data-ice="title">src/TempoInduction.js | API Document</title> <link type="text/css" rel="stylesheet" href="css/style.css"> <link type="text/css" rel="stylesheet" href="css/prettify-tomorrow.css"> <script src="script/prettify/prettify.js"></script> <script src="script/manual.js"></script> </head> <body class="layout-container" data-ice="rootContainer"> <header> <a href="./">Home</a> <a href="identifiers.html">Reference</a> <a href="source.html">Source</a> <a data-ice="repoURL" href="https://github.com/killercrush/music-tempo" class="repo-url-github">Repository</a> <div class="search-box"> <span> <img src="./image/search.png"> <span class="search-input-edge"></span><input class="search-input"><span class="search-input-edge"></span> </span> <ul class="search-result"></ul> </div> </header> <nav class="navigation" data-ice="nav"><div> <ul> <li data-ice="doc"><span data-ice="kind" class="kind-class">C</span><span data-ice="name"><span><a href="class/src/Agent.js~Agent.html">Agent</a></span></span></li> <li data-ice="doc"><span data-ice="kind" class="kind-class">C</span><span data-ice="name"><span><a href="class/src/BeatTracking.js~BeatTracking.html">BeatTracking</a></span></span></li> <li data-ice="doc"><span data-ice="kind" class="kind-class">C</span><span data-ice="name"><span><a href="class/src/FFT.js~FFT.html">FFT</a></span></span></li> <li data-ice="doc"><span data-ice="kind" class="kind-class">C</span><span data-ice="name"><span><a href="class/src/MusicTempo.js~MusicTempo.html">MusicTempo</a></span></span></li> <li data-ice="doc"><span data-ice="kind" class="kind-class">C</span><span data-ice="name"><span><a href="class/src/OnsetDetection.js~OnsetDetection.html">OnsetDetection</a></span></span></li> <li data-ice="doc"><span data-ice="kind" class="kind-class">C</span><span data-ice="name"><span><a href="class/src/TempoInduction.js~TempoInduction.html">TempoInduction</a></span></span></li> </ul> </div> </nav> <div class="content" data-ice="content"><h1 data-ice="title">src/TempoInduction.js</h1> <pre class="source-code line-number raw-source-code"><code class="prettyprint linenums" data-ice="content">/** * Performs tempo induction by finding clusters of similar inter-onset intervals (IOIs) * @class */ export default class TempoInduction { /** * Find clusters * @param {Array} events - the onsets from which the tempo is induced * @param {Object} [params={}] - parameters * @param {Number} [params.widthTreshold=0.025] - the maximum difference in IOIs which are in the same cluster * @param {Number} [params.maxIOI=2.5] - the maximum IOI for inclusion in a cluster * @param {Number} [params.minIOI=0.07] - the minimum IOI for inclusion in a cluster * @return {{clIntervals: Array, clSizes: Array}} - object with clusters */ static processRhythmicEvents(events, params = {}) { const widthTreshold = params.widthTreshold || 0.025, maxIOI = params.maxIOI || 2.5, minIOI = params.minIOI || 0.07, length = events.length; let clIntervals = [], clSizes = [], clCount = 0; for (let i = 0; i < length - 1; i++) { for(let j = i + 1; j < length; j++) { let ioi = events[j] - events[i]; if (ioi < minIOI) { continue } if (ioi > maxIOI) { break; } let k = 0; for ( ; k < clCount; k++) { if (Math.abs(clIntervals[k] - ioi) < widthTreshold) { if ( Math.abs(clIntervals[k + 1] - ioi) < Math.abs(clIntervals[k] - ioi) && k < clCount - 1 ) { k++; } clIntervals[k] = (clIntervals[k] * clSizes[k] + ioi) / (clSizes[k] + 1); clSizes[k]++; break; } } if (k != clCount) continue; clCount++; for ( ; k > 0 && clIntervals[k - 1] > ioi; k--) { clIntervals[k] = clIntervals[k - 1]; clSizes[k] = clSizes[k - 1]; } clIntervals[k] = ioi; clSizes[k] = 1; } } if (clCount == 0) { throw "Fail to find IOIs"; } clIntervals.length = clCount; clSizes.length = clCount; return {clIntervals, clSizes}; } /** * Merge similar intervals * @param {Object} clusters - object with clusters * @param {Array} clusters.clIntervals - clusters IOIs array * @param {Array} clusters.clSizes - clusters sizes array * @param {Object} [params={}] - parameters * @param {Number} [params.widthTreshold=0.025] - the maximum difference in IOIs which are in the same cluster * @return {{clIntervals: Array, clSizes: Array}} - object with clusters */ static mergeClusters(clusters, params = {}) { const widthTreshold = params.widthTreshold || 0.025; let clIntervals = clusters.clIntervals, clSizes = clusters.clSizes; let clCount = clIntervals.length; for (let i = 0; i < clCount; i++) for (let j = i + 1; j < clCount; j++) if (Math.abs(clIntervals[i] - clIntervals[j]) < widthTreshold) { clIntervals[i] = (clIntervals[i] * clSizes[i] + clIntervals[j] * clSizes[j]) / (clSizes[i] + clSizes[j]); clSizes[i] = clSizes[i] + clSizes[j]; --clCount; for (let k = j + 1; k <= clCount; k++) { clIntervals[k-1] = clIntervals[k]; clSizes[k-1] = clSizes[k]; } } clIntervals.length = clCount; clSizes.length = clCount; return {clIntervals, clSizes}; } /** * Score intervals * @param {Object} clusters - object with clusters * @param {Array} clusters.clIntervals - clusters IOIs array * @param {Array} clusters.clSizes - clusters sizes array * @param {Object} [params={}] - parameters * @param {Number} [params.widthTreshold=0.025] - the maximum difference in IOIs which are in the same cluster * @param {Number} [params.maxTempos=10] - initial amount of tempo hypotheses * @return {{clScores: Array, clScoresIdxs: Array}} - object with intervals scores */ static calculateScore(clusters, params = {}) { const widthTreshold = params.widthTreshold || 0.025; let maxTempos = params.maxTempos || 10; let clIntervals = clusters.clIntervals, clSizes = clusters.clSizes, clScores = [], clScoresIdxs = []; let clCount = clIntervals.length; for (let i = 0; i < clCount; i++) { clScores[i] = 10 * clSizes[i]; clScoresIdxs[i] = { score: clScores[i], idx: i}; } clScoresIdxs.sort( (a, b) => b.score - a.score ); if (clScoresIdxs.length > maxTempos) { for (let i = maxTempos - 1; i < clScoresIdxs.length - 1; i++) { if (clScoresIdxs[i].score == clScoresIdxs[i + 1].score) { maxTempos++; } else { break; } } clScoresIdxs.length = maxTempos; } clScoresIdxs = clScoresIdxs.map( a => a.idx ); for (let i = 0; i < clCount; i++) { for (let j = i + 1; j < clCount; j++) { let ratio = clIntervals[i] / clIntervals[j]; let isFraction = ratio < 1; let d, err; d = isFraction ? Math.round(1 / ratio) : Math.round(ratio); if (d < 2 || d > 8) continue; if (isFraction) err = Math.abs(clIntervals[i] * d - clIntervals[j]); else err = Math.abs(clIntervals[i] - clIntervals[j] * d); let errTreshold = isFraction ? widthTreshold : widthTreshold * d; if (err >= errTreshold) continue; d = d >= 5 ? 1 : 6 - d; clScores[i] += d * clSizes[j]; clScores[j] += d * clSizes[i]; } } return {clScores, clScoresIdxs}; } /** * Get array of tempo hypotheses * @param {Object} clusters - object with clusters * @param {Array} clusters.clIntervals - clusters IOIs array * @param {Array} clusters.clSizes - clusters sizes array * @param {Array} clusters.clScores - clusters scores array * @param {Array} clusters.clScoresIdxs - clusters scores indexes array * @param {Object} [params={}] - parameters * @param {Number} [params.widthTreshold=0.025] - the maximum difference in IOIs which are in the same cluster * @param {Number} [params.minBeatInterval=0.3] - the minimum inter-beat interval (IBI) (0.30 seconds == 200 BPM) * @param {Number} [params.maxBeatInterval=1] - the maximum inter-beat interval (IBI) (1.00 seconds == 60 BPM) * @return {Array} tempoList - tempo hypotheses array */ static createTempoList(clusters, params = {}) { const widthTreshold = params.widthTreshold || 0.025, minBeatInterval = params.minBeatInterval || 0.3, maxBeatInterval = params.maxBeatInterval || 1; let clIntervals = clusters.clIntervals, clSizes = clusters.clSizes, clScores = clusters.clScores, clScoresIdxs = clusters.clScoresIdxs, tempoList = []; let clCount = clIntervals.length; for (let i = 0; i < clScoresIdxs.length; i++) { let idx = clScoresIdxs[i]; let newSum = clIntervals[idx] * clScores[idx]; let newWeight = clScores[idx]; let err, errTreshold; for (let j = 0; j < clCount; j++) { if (j == idx) continue; let ratio = clIntervals[idx] / clIntervals[j]; let isFraction = ratio < 1; let sumInc = 0; let d = isFraction ? Math.round(1 / ratio) : Math.round(ratio); if (d < 2 || d > 8) continue; if (isFraction) { err = Math.abs(clIntervals[idx] * d - clIntervals[j]); errTreshold = widthTreshold; } else { err = Math.abs(clIntervals[idx] - d * clIntervals[j]); errTreshold = widthTreshold * d; } if (err >= errTreshold) continue; if (isFraction) { newSum += clIntervals[j] / d * clScores[j]; } else { newSum += clIntervals[j] * d * clScores[j]; } newWeight += clScores[j]; } let beat = newSum / newWeight; while (beat < minBeatInterval) beat *= 2; while (beat > maxBeatInterval) beat /= 2; tempoList.push(beat); } return tempoList; } }</code></pre> </div> <footer class="footer"> Generated by <a href="https://esdoc.org">ESDoc<span data-ice="esdocVersion">(0.5.2)</span><img src="./image/esdoc-logo-mini-black.png"></a> </footer> <script src="script/search_index.js"></script> <script src="script/search.js"></script> <script src="script/pretty-print.js"></script> <script src="script/inherited-summary.js"></script> <script src="script/test-summary.js"></script> <script src="script/inner-link.js"></script> <script src="script/patch-for-local.js"></script> </body> </html>